Implement QXmlStreamReader::hasStandaloneDeclaration()

This patch implements a public getter for the hasStandalone attribute.
It returns true, if standalone has been explicitly declared in an XML
header and false otherwise.

As this is no longer necessary it removes accessing QXmlStreamPrivate
from QDomParser.

[ChangeLog][QtCore][QXmlStreamReader] added hasStandaloneDeclaration()

Change-Id: Iaaa0a728a6f7186e40637186077f7b49c112f7a9
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Yuhang Zhao <yuhangzhao@deepin.org>

src/corelib/serialization/qxmlstream.cpp

@@ -2692,6 +2692,8 @@ bool QXmlStreamReader::isCDATA() const
   XML declaration; otherwise returns \c false.
 
   If no XML declaration has been parsed, this function returns \c false.
+
+  \sa hasStandaloneDeclaration()
  */
 bool QXmlStreamReader::isStandaloneDocument() const
 {
@@ -2699,6 +2701,21 @@ bool QXmlStreamReader::isStandaloneDocument() const
     return d->standalone;
 }
 
+/*!
+  \since 6.6
+
+  Returns \c true if this document has an explicit standalone
+  declaration (can be 'yes' or 'no'); otherwise returns \c false;
+
+  If no XML declaration has been parsed, this function returns \c false.
+
+  \sa isStandaloneDocument()
+ */
+bool QXmlStreamReader::hasStandaloneDeclaration() const
+{
+    Q_D(const QXmlStreamReader);
+    return d->hasStandalone;
+}
 
 /*!
      \since 4.4

src/corelib/serialization/qxmlstream.h

@@ -246,6 +246,7 @@ public:
     inline bool isProcessingInstruction() const { return tokenType() == ProcessingInstruction; }
 
     bool isStandaloneDocument() const;
+    bool hasStandaloneDeclaration() const;
     QStringView documentVersion() const;
     QStringView documentEncoding() const;
 

src/corelib/serialization/qxmlstream_p.h

@@ -510,8 +510,6 @@ public:
 
     QXmlStreamEntityResolver *entityResolver;
 
-    static QXmlStreamReaderPrivate *get(QXmlStreamReader *q) { return q->d_func(); }
-
 private:
     /*! \internal
        Never assign to variable type directly. Instead use this function.

src/xml/dom/qdomhelpers.cpp

@@ -266,8 +266,7 @@ bool QDomParser::parseProlog()
                     value += u" standalone='yes'"_s;
                 } else {
                     // Add the standalone attribute only if it was specified
-                    QXmlStreamReaderPrivate *priv = QXmlStreamReaderPrivate::get(reader);
-                    if (priv->hasStandalone)
+                    if (reader->hasStandaloneDeclaration())
                         value += u" standalone='no'"_s;
                 }